Several pipe joining methods are known. Many pipe joints have a bell, a pin, and are characterized by an external clamping ring around the bell. The pin may be sealed with a suitable adhesive material.
U.S. Pat. No. 3,208,136 describes a method which consists of forming a bell on one pipe, and rolling an annular groove in the end of the other pipe. The grooved end is only partially telescoped inside the bell with sufficient force to cause the walls of the groove to slightly buckle.
Pipes used in the oil industry for transporting hydrocarbon products are internally coated. Conventional pipe joints are vulnerable to chemical attack, especially in the region, known as the "mouth", where the end wall of the pin makes contact with the inner wall of the bell.
This invention provides a pipe joint that is mechanically very strong, that is relatively inexpensive to make or to repair in the field, and that is capable of carrying corrosive fluids, such as hydrocarbon products, under substantial pressure. An internal, flexible, adhesive, pore-free ring is automatically formed at the mouth of the joint during the connection process. This ring blends with the internal pipe coatings to protect the mouth of the connection against corrosion.